Virginia M. Sanders

Humoral and cell-mediated immune status in mice exposed to trichloroethylene in the drinking water☆

Abstract A 14-day study using male CD-1 mice exposed to trichloroethylene (TCE) by daily po gavage suggested inhibition of cell-mediated immunity. Therefore, an evaluation of the immune status was undertaken after exposure of male and female mice to TCE in the drinking water for either 4 or 6 months. The immunological parameters assessed were humoral immunity, cell-mediated immunity, lymphocyte responsiveness, bone marrow function, and macrophage function. Females were more affected than males by TCE, particularly after a 4-month exposure. In the female, humoral immunity was inhibited only at the highest concentrations of TCE (2.5 and 5 mg/ml), whereas cell-mediated immunity and bone marrow stem cell colonization were inhibited at all four concentrations of TCE (0.1, 1.0, 2,5, and 5 mg/ml). The males were relatively unaffected after both 4 and 6 months compared to effects observed in the 14-day study.

Toxicology of trichloroethylene in the mouse

Abstract The purpose of this study was to evaluate the acute and subchronic toxicology of trichloroethylene (TCE) in the mouse. The oral LD50 in female mice was 2443 mg/kg (95% confidence limits of 1839–3779 mg/kg) and in male mice was 2402 mg/kg (95% confidence limits of 2065–2771 mg/kg). After determination of the LD50 by the oral route, a 14-day study was done in male CD-1 mice in which TCE was administered daily by gavage at 24 and 240 mg/kg. A subchronic drinking water study was designed based on these data, in which TCE at concentrations of 0.1, 1.0, 2.5, and 5.0 mg/ml was used, and mice of both sexes were exposed for 4 or 6 months. There was a decreased body weight gain at the highest dose, which could be attributed to a decrease in fluid consumption. The most significant effects attributable to TCE were an increase in liver weight in both sexes accompanied by increased nonprotein sulfhydryl levels in the males, and an increase in kidney weight in both sexes accompanied by increases in protein and ketones in the urine. TCE failed to elicit any other adverse effects.

Immunotoxicological Investigations in the Mouse: General Approach and Methods

The adverse effects of chemicals on the lymphoreticular system have generated considerable toxicological interest. In this series of papers, the effects of selected environmentally relevant compounds are reported. This first paper describes the methods and general approach used in judging a chemicals potential risk to the immune system. Risk evaluation was approached utilizing acute, 14- and 90-day studies. Both sexes of the CD-1 random-bred mouse were employed. The immune system was evaluated against a background of more standard toxicological parameters, which included fluid consumption, body and organ weights, hematology, serum and liver chemistries, hepatic microsomal enzyme activities and blood coagulation. Bone marrow status was evaluated by assessing DNA synthesis. Humoral immunity was evaluated by determining the number of IgM spleen antibody-forming cells (AFC) to sheep erythrocytes (sRBC), the serum antibody level to sRBC, and spleen lymphocyte response to the B cell mitogen, lipopolysaccharide (LPS). The status of cell-mediated immunity was assessed by quantitating the delayed type hypersensitivity (DTH) response to sRBC, proliferation of the popliteal lymph node, and the spleen cell response to the T lymphocyte mitogen, Concanavalin A (Con A). Macrophage function was evaluated by measurement of the vascular clearance rate and distribution of radiolabeled sRBC in the liver, spleen, lungs, and thymus, and recruitability, adherence, chemotaxis, and phagocytic activity of peritoneal exudate cells (PEC). Historical control data from six 14- and 90-day studies conducted over a one year period are given. The data resulting from these types of studies can provide a basis for the initial evaluation of a chemicals adverse effect on the immune system.

TOXICOLOGY OF TRANS-1,2-DICHLOROETHYLENE IN THE MOUSE

Trans-1,2-dichloroethylene (DCE) was administered to male and female CD-1 mice in order to evaluate its effects on standard toxicological parameters. Following an acute LD50 determination (2122 mg/kg in males and 2391 mg/kg in females) and a 14-day range-finding study, a 90-day drinking water study was performed using levels of DCE calculated to deliver approximately 1/100, 1/10, and 1/5 the LD50. Various toxicological assessments were made, including body and organ weights, hematology, serum chemistries, and hepatic microsomal activities. Few alterations were observed in either sex following 90 days of exposure. The most noteworthy changes occurred in the males exposed to the highest level of DCE, where there was a significant decrease in glutathione levels, and in the females exposed to all three DCE levels, where there was a significant decrease in aniline hydroxylase activity. These data served as background for the immunotoxicological evaluation presented in the following manuscript.

Effects of piperonyl butoxide on dimethylnitrosamine metabolism and toxicity in Swiss mice.

The effects of piperonyl butoxide (PB) on the metabolism and toxicity of dimethylnitrosamine (DMN) in Swiss mice were determined. PB, at doses of 10 and 20 mg/kg, inhibited DMN demethylase 45 min after treatment by 18 and 37%. These inhibitory effects were marked 0.5 hr after PB (640 mg/kg) treatment and reached maximal effects at 2 hr when there was 55% inhibition of enzyme activity. The inhibition by PB continued for 24 hr where enzyme activity was suppressed by 35%. At 48 hr after treatment there was stimulation of enzyme activity. Enzyme kinetic determinations showed no change in Km but Vmax decreased from 129 to 49 mumol CH2O/min-g liver. PB (640 mg/kg) inhibited DMN (500 mg/kg; im) mutagenicity in the host-mediated assay, decreasing the mutant frequency by 42%. Paradoxically, PB (640 mg/kg) had no effect on the alkylation of nucleic acids or proteins in mouse liver, kidney, lung, or spleen. In addition, pretreatment with PB (640 mg/kg) had no effect on the LD50 of DMN.

Humoral and Cell-Mediated Immune Status of Mice Exposed to Trans-1,2-Dichloroethylene

This study assessed possible adverse immunological effects of trans-1,2-dichloroethylene (DCE) on random-bred CD-1 mice following 14 and 90 days of exposure. A 14-day range-finding study was performed on male mice by gavage at doses 1/10 and 1/100 the LD50 (210 and 21 mg/kg). No alterations in either humoral or cell-mediated immunity were observed following this exposure. A 90-day study was conducted in which DCE was administered in the drinking water of male and female mice. The levels of DCE in the drinking water were calculated to deliver levels equivalent to, and higher than, those delivered for 14 days (17, 175, and 387 mg/kg for males and 23, 224, and 452 mg/kg for females). No changes were observed in the cell-mediated immune status of either sex or in the humoral immune status of females. However, a marked suppression in humoral immune status was observed in male mice exposed to all three levels of DCE, as indicated by a decreased ability of spleen cells to produce antibody against sheep erythrocytes (sRBC). Macrophage function was depressed only in females, as indicated by the decreased ability of thioglycollate-recruited peritoneal exudate cells (PEC) to phagocytize sRBC.

Humoral and Cell-Mediated Immune Status of Mice Exposed to 1,1,2-Trichloroethane

The purpose of this study was to assess the immunological effects of 1,1,2-trichloroethane (TCE) on random-bred CD-1 mice following 14 and 90 days of oral exposure. A toxicological evaluation conducted at the same time revealed the target organs to be the liver of both sexes and the erythroid elements of the females. The 14-day immunological range-finding study in males exposed to doses 1/10 and 1/100 the LD50 (38 and 3.8 mg/kg) revealed no alterations in either humoral or cell-mediated immune status. Following 90 days of exposure in the drinking water (4.4., 46, and 305 mg/kg for males and 3.9, 44, and 384 mg/kg for females), a more detailed series of immunological parameters was assessed. Cell-mediated immunity was unaltered in both sexes, while humoral immune status was depressed in both sexes, particularly when determined by hemagglutination titers. Macrophage function was depressed only in the males as indicated by the ability of thioglycolate-recruited peritoneal exudate cells (PEC) to phagocytize sheep erythrocytes (sRBC).

Toxicology of 1,1,2-Trichloroethane in the Mouse

1,1,2-Trichloroethane (TCE) was administered to male and female CD-1 mice to evaluate its effect on standard toxicological parameters. Following determination of the acute LD50 (378 mg/kg in males and 491 mg/kg in females), and a 14-day range-finding study, a 90-day drinking water study was performed in which the doses consumed were 4.4, 46, and 305 mg/kg for males and 3.9, 44, and 384 mg/kg for females. The liver was a target of TCE toxicity in both sexes as demonstrated by dose-dependent alterations in hepatic microsomal enzyme activities and serum enzyme levels. The erythroid element of the female mice was also affected, as indicated by significantly decreased hematocrit and hemoglobin levels.

Suppression of dimethylnitrosamine metabolism and toxicity by nitrososarcosine and other nitrosamines.

Groups of rats were pretreated with nitrososarcosine (NS), diethylnitrosamine (DEN), or dibutylnitrosamine (DBN) in order to observe potential effects on dimethylnitrosamine (DMN) toxicity and metabolism. NS and DEN completely suppressed DMN-induced inhibition of liver protein synthesis while the case with DBN was not as clear. DMN metabolism was effected by suppression of DMN demethylase activity, and an inhibition of RNA, DNA, and protein methylation by [14C]DMN by each nitroso compound.

Acute toxicity of dimethylnitrosamine in the presence of inhibitors of DMN demethylase.

The LD50 of DMN was determined in groups of mice in the presence of inhibitors of DMN demethylase. Piperonyl butoxide, dibutylnitrosamine and nitrososarcosine had no effect on the acute toxicity of DMN. Diethylnitrosamine and DMN were markedly synergistic. All mice treated with 100 mg/kg diethylnitrosamine and 10.7 mg/kg DMN died. These results suggest that DMN demethylase may not be involved in theaacute toxicity of DMN.